Method for setting hair with dithiourea and derivatives thereof



3,534,135 METHOD FOR SETTING HAIR WITH DITHIOUREA AND DERIVATIVES THEREOF Theodor Wajaroff, Darmstadt, Germany, assignor to Wella Aktiengesellschaft, Dai-mstadt, Germany No Drawing. Filed Dec. 20, 1966, Ser. No. 603,398

Claims priority, application Germany, Dec. 23, 1965, W 40,583

Int. Cl. A61k 7/10 US. Cl. 42471 9 Claims ABSTRACT OF THE DISCLOSURE A method of setting hair which has been softened by splitting disulfide bridges between protein chains of the hair keratin by applying to the hair, in a suitable carrier material, an effective amount of a salt of dithiourea (diformamidine disulfide) or of an N-alkyl derivative of dithiourea, and a hair setting composition consisting essentially of such salt dissolved in a carrier liquid which is compatible with hair.

BACKGROUND OF THE INVENTION The present invention relates to setting or fixing hair, more particulraly to setting hair which, in softened condition has been subjected to permanent waving. According to the present invention a hair setting composition and a method of setting hair are provided which will restore the disulfide bridges between protein chains of the keratin of the hair which were split by means of reducing agents such as thioglycolates in order to make the hair sufficiently deformable for the permanent waving of the same. Thus, by restoring the disulfide bridges in accordance with the present invention, the hair will be set or fixed in the shape given to it by permanent waving while such disulfide bridges had been split.

The problems of again cross-linking the protein chains has been considered for some length of time. Generally, the agents used for cross-linking softened hair have to be reactive with respect to the mercapto groups which were formed during the softening of the hair.

Thus, bifunctional compounds were suggested as fixing agents, which by reaction of their functional groups with the SH groups of adjacent protein chains are capable to form a molecular bridge, and thereby permanently set the hair in the shape given to the same. However, these compounds, including the bridges between the protein chains are different from the compounds present in the natural hair structure and, furthermore, cause irreversible and disadvantageous changes in the structure of the hair.

In view thereof, it would be more desirable to set the hair with compounds which will permit restoration of the natural disulfide bonds of the hair keratin without retention of foreign matter, i.e., compounds alien to the natural hair composition, in the hair.

Suitable for this purpose are several oxidizing agents and, in fact, for the setting of permanent waves, hydrogen peroxide and addition products thereof such as urea peroxide and alkali perborates as well as salts of oxygencontaining hydrohalic acids such as alkali metal bromates and chlorites have been used.

These fixing or setting agents, however, have a relatively high oxidation potential so that the mercapto groups which were formed in the process of softening the hair are partly oxidized beyond the desired disulfide stage to higher oxidation stages. Thereby, the corresponding sulfoxides and even sulfonic groups are formed in the keratin of the hair. These side reactions cause damage to the structure of the hair and a reduction of the number of active groups 3,534,135 Patented Oct. 13, 1970 which are required for the redox process of the permanent waving.

Furthermore, the handling and storing of these preparations is difficult and frequently dangerous since they are sometimes capable of spontaneous decomposition. ln the case of bromates the further disadvantage of high infiammability exists, and in the case of peroxides frequently undesirable and harmful bleaching of the hair will be caused.

Furthermore, alkali metal polythionates were proposed for the fixing of permanent waves, because these last-mentioned compounds, due to their very mild oxidizing effect, would not cause any damage to the hair. However, it has been found that the last-mentioned compounds are incapable of achieving the desired degree of fixing of the hair so that permanently waved hair treated in this manner will not be sufficiently resistant against humidity or moisture and under such conditions will lose its shape. It appears that the effect of the polythionates is too weak to cause the conversion of a sufficiently large proportion of the SH groups of the softened hair into cross-lined SS bridges.

It is an object of the present invention to solve the above discussed problems and difficulties.

SUMMARY OF THE INVENTION According to the present invention the softened permanently waved hair is effectively set without forming in the hair structure any compounds which are foreign to natural hair, by applying to the softened hair a hair setting composition which consists essentially of a carrier material which is compatible with hair and in which is distributed a salt of dithiourea (diformamidine disulfide) or of an N-alkyl derivative of dithiourea.

Preferably, the above described effective salt is dissolved in an aqueous liquid as the carrier material and the N-alkyl derivative preferably is a N-lower alkyl derivative.

The effective proportion of the above described salts generally will be between about 2% by weight of the hair setting composition and a maximum percentage which equals the concentration of a saturated solution of the salt in the aqueous liquid.

Application of hair setting composition as described above will cause substantial restoration of the initial disulfide bridges between the protein chains of the hair keratin which were split in order to soften the hair so as to make it amenable to waving or other deformation.

While the hair deformation is referred to herein generally as hair waving, the present invention is not limited to the setting or fixing of permanently waved hair but can also be utilized in connection with the setting or fixing of, for instance, straightened hair, or hair which for whatever reason had been softened under splitting of the above described disulfide bridges.

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the present invention, one or more salts of dithiourea or of N-alkyl derivatives thereof are used for the fixing or setting of the softened, for instance permanently waved, hair.

The effect of the salts of the present invention with respect to restoration of the disulfide bridges of the hair keratin is schematically illustrated by the following equation:

By proceeding in accordance with the present invention, the excessive oxidation of the disulfide bonds to higher oxidation stages is avoided and, on the other hand, it is assured that a sufficient number of disulfide bonds or bridges will be restored. It is thus possible to achieve a result with respect to the fixing of the hair which with respect to avoiding damage to the hair as well as with respect to the strength and permanency of the shape retention of the hair, for instance, the permanent wave thereof, satisfies all requirements.

The salts of the N-alkyl derivatives which may be used in accordance with the present invention are preferably N-lower-alkyl derivatives, since higher alkyl derivatives of this kind are of markedly reduced effectiveness.

It is necessary to use salts of thiourea or of the above described derivatives thereof, since the free bases are unstable.

The type of the anion of these salts is substantially without significance. Preferably, the chlorides or bromides are used but good results are also obtained by utilizing other organic or inorganic salts of thiourea or of N-loWeralkyl derivatives thereof, for instance, nitrates or oxalates.

Broadly, the salts which form the effective setting agent of the present invention have the following structural formula:

wherein R denotes either hydrogen or an alkyl group, and the alkyl group preferably is methyl, ethyl or propyl. It will be noted that the structural formula includes four secondary valences C N.

By using the setting composition of the present invention, it is possible to obtain a hairdo which is highly resistant against moisture and will substantially maintain its shape even after several washings of the hair. The results obtained in this manner are also highly satisfactory with respect to the requirements of combing and dressing of the hair.

The salts of dithiourea and derivatives thereof which are used according to the present invention are stable in solid condition and are also harmless when stored and used in solution since they tend neither to spontaneous decomposition nor is there any danger of inflammation.

Preferably, the salts are used in an acidic aqueous solution since these salts have their best fixing effect in an acidic medium and, on the other hand, when applied in an acidic solution, the alkaline permanent waving solution will be quickly neutralized so that the conventional acidic rinse can be dispensed with.

Furthermore, the dithiourea compounds which are utilized according to the present invention tend in weak acidic solutions slowly to split off colloidal sulfur. This phenomenon also takes place during contact of the hair setting composition of the present invention on the hair with alkaline hair waving solution. It is well known that elementary sulfur has a disinfecting and generally favorable effect on the scalp so that the slow formation of colloidal sulfur represents another favorable side effect of the present invention.

The effective salts which are utilized according to the present invention may be combined with suitable, preferable aqueous carrier substances which are compatible with hair, as well as with other preparations and additives of hair cosmetic preparations, such as emulsifiers, wetting agents, thickeners and the like.

The concentration of the salts of thiourea and/or the above described derivatives thereof in the hair setting composition according to the present invention generally will be at least equal to 2% of the weight of the hair setting composition and preferably equal to between about 5% and of the weight thereof. The upper limit of the 4 concentration will be that of a saturated solution of the effective salt in the carrier liquid.

The following examples are given as illustrative only, without, however, limiting the invention to the specific details of the examples.

EXAMPLE I 8.0 g. dithiourea-dichloride and 0.8 g. sodiumlaurylsulfate (Texapon Z highly concentrated) are dissolved in ml. water, and the pH of the solution is 1.8.

One-half of the thus obtained solution is foamed onto the hair while the same is wound on curlers or rollers and allowed to react with the hair for about 3 minutes. Thereafter, the curlers or rollers are removed and the other half of the solution is foamed onto the hair and again allowed to react for 3 minutes. This is followed by rinsing, and thereby the hair setting is completed.

EXAMPLE II 12.0 g. dithiourea-dibromide and 1.0 g. laurylpyridinechloride are dissolved in ml. water, and the pH of the solution is 2.0.

The hair treatment is carried out as described in Example I.

EXAMPLE III 12.0 g. dithiourea-dichloride, 2.0 g. thiourea and 3.0 g. dry perfume (polyglycol 10,000 with 15% perfume oil) are dissolved in 100 ml. water, and the pH of the solution is 1.8.

One-half of the solution is applied to the hair while the same is wound on curlers and allowed to react for 3 minutes. Thereafter, the curlers are removed and the other half of the solution is applied to the hair and again allowed to react for 3 minutes, followed by rinsing with water.

EXAMPLE IV 30.9 g. dithiourea-dichloride and 22.0 g. disodiumhydrogenphosphate- 12 H O are dissolved in 500 ml. water, to form a solution having a pH of 4.0.

Half of this solution is rinsed onto the hair while the same is wound about curlers and allowed to react for 3 minutes. Thereafter, the curlers are removed and the other half of the solution is rinsed over the hair and is again allowed to react for about 3 minutes, followed by rinsing with water.

EXAMPLE V 20.0 g. N,N-diisopropyl-dithiourea-dibromide are dissolved in 500 ml. water, to form a solution having a pH of 2.2.

The hair is treated with the thus formed solution as described in Example IV.

EXAMPLE VI 10.0 g. N,N-diethyl-dithiourea-dibromide are dissolved in 100 ml. water, to form a solution having a pH of 2.2.

The hair is then set as described in Example III.

EXAMPLE VII 8.0 g. N,N-dimethyl-dithiourea-dibromide and 0.6 g. sodiumlaurylsulfate (Texapon Z, highly concentrated) are dissolved in 60 ml. water, to form a solution having a pH of 1.9.

The hair is treated with the thus formed solution, as described in Example I.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

1. Method for setting hair which has been softened by splitting disulfide bridges between protein chains of the hair keratin, comprising the steps of applying to said thus softened hair a hair setting composition consisting essentially of an aqueous carrier which is compatible with hair and having distributed therethrough an effective amount of a substance selected from the group consisting of a water-soluble salt of diformamidine disulfide and N-lower alkyl derivatives thereof.

2. A method as defined in claim 1, wherein said aqueous carrier has an acid pH and wherein said substance is dissolved in said carrier.

3. A method as defined in claim 1, wherein said substance is selected from the group consisting of the chlorides, bromides, nitrates and oxalates of diformarnide disulfide and N,N-dimethyl, N,N-diethyl and N,N-diisopropyl derivatives thereof.

4. A method as defined in claim 1, wherein said salt is selected from the group consisting of chlorides, bromides, nitrates and oxalates.

5. A method as defined in claim 1, wherein said loweralkyl is selected from the group consisting of methyl, ethyl and propyl.

6. A method as defined in claim 2, wherein said efi ective amount is equal to between about 2% by weight of said hair setting composition and the saturation concentration of said substance in said aqueous carrier.

7. A method as defined in claim 2, wherein said eifective amount is about equal to between 5 and 15% by weight of said hair setting composition.

References Cited UNITED STATES PATENTS 2,195,623 4/1940 Harman 260564 X 2,783,272 2/1957 Young 260 -564 X 2,853,132 9/1958 Sallmann et al. 424-320 X ALBERT T. MEYERS, Primary Examiner V. C. CLARKE, Assistant Examiner US. Cl. X.R. 

